This is a Phase II study designed to estimate the efficacy of weekly low-dose PEG-Intron in pediatric patients with CNS tumors, beginning 2-10 weeks after completion of radiation therapy. The endpoint of the trial is 2-year survival compared to historical controls who have received radiation alone. To date, 22 patients have been enrolled. All patients have tolerated the PEG-Intron therapy well, with no adverse events directly attributable to the study agent. The study is enrolling 24 patients and taking an early look for efficacy. The study is ongoing.